It is a common practice in the industry to blend a small amount of elastomeric or thermoplastic material into a hard thermosetting resin in order to toughen (i.e., increase the ductility of) the thermoset. Elastomeric or thermoplastic toughening agents include natural rubbers, polyolefins, and vinyl copolymers such as poly(styrene-co-butadiene). In such cases, the toughening agent is blended in a ratio of from about 1:20 to about 1:4 with a curable thermosetting resin such that the thermoplastic component becomes the dispersed phase in a thermosetting resin continuous phase.
U.S. Pat. No. 5,709,948 discloses curable mixtures of polyolefin resins and epoxies. Curable mixtures comprising PPEs are not disclosed.
EP 592,145 and U.S. Pat. No. 4,912,172 disclose curable compositions consisting essentially of a polyphenylene ether (PPE), an epoxy, a zinc or aluminum catalyst, and, in some cases, an imide co-catalyst. These references do not teach that a curable melt processed composition of greater than 50% thermoplastic can be obtained. These references disclose solvent mixing of the components or mixing wherein a liquid epoxy is the major component. These references do not teach the use of a PPE/HIPS blend thermoplastic. These references disclose materials for structural use rather than for use as adhesives or coatings.
U.S. Pat. No. 5,001,010 discloses a curable article comprising a mixture of an epoxy and an epoxy cure catalyst with a specific PPE obtained by melt processing the PPE at 230° C.-290° C. prior to addition of epoxy. This reference discloses solvent mixing of the epoxy with the melt-processed PPE and subsequent cure at 190° C.-250° C.
U.S. Pat. No. 5,308,565 discloses a prepreg board made with reinforcing fiber and a curable composition which preferably comprises PPE, a liquid epoxy, a flame retardant, and a curing catalyst, but at least comprising the first two elements. The blend is partially cured during mixing ('565 at col. 2, ln. 50) at 100-130° C., so that it can be granulated and mixed with a substrate for final curing to form a mat. The reference emphasizes throughout that the mixing is performed at 100-130° C. The reference recommends an epoxy content of greater than 50%. ('565 at col. 13, ln. 31). This reference discloses materials for structural use rather than for use as adhesives or coatings.
EP 137,545 discloses an article made from a blend of PPE, HIPS and an epoxy resin which is coated with a lacquer or adhesive. The material of the reference is required to receive a coating or adhesive and is not disclosed as being suitable for use as a coating or adhesive. The reference does not teach that the epoxy component is cured or uncured at any point. The reference does not teach curing the epoxy component or the inclusion of any curative or catalyst.
Venderbosch, Nelissen, Meijer and Lemstra, Makromol. Chem., Macromol. Symp. 75, pp. 73-84 (1993); Venderbosch, Meijer and Lemstra, POLYMER, Vol. 35, no. 20, pp. 4349-4357 (1994); and Venderbosch, Meijer and Lemstra, POLYMER, Vol. 36, no. 6, pp. 1167-1178 (1995) disclose melt mixing combinations of PPE and epoxy monomers. These references do not describe PPE/PS/epoxy mixtures nor the use of compatiblizers with such mixtures.